Disclosed are sensing systems and methods that eliminate CPU intervention or interrupts when performing sensor scans of a touch interface, supports low power sensing operation without requiring periodic wake up of the CPU, and is scalable to multi-channel or multi-chip sensor configuration to support large touch screens or a high number of sensors. A sensor scanning module may operate in a chained-scan using direct memory access (CS-DMA) mode or an autonomous scan-multiple scan (AS-MS) mode to perform scanning of all sensors within a frame without requiring CPU intervention or generating CPU interrupts after every scan in the frame. The sensor scanning module may operate autonomously in a low-power always-on scan (LP-AOS) mode for multiple frames without CPU interaction until a touch event is detected. The CPU may operate in a low power sleep mode during the scan while providing consistent refresh rate and low touch-to-system wake up latency.
Legal claims defining the scope of protection, as filed with the USPTO.
2. The capacitive sensing device of claim 1, wherein the first group and the second group are mutually exclusive capacitive sensors.
3. The capacitive sensing device of claim 1, wherein to load, without intervention by the processor, the first sensor configuration or the second sensor configuration, the ACSS is configured to load the first sensor configuration or the second sensor configuration through a direct memory access (DMA) channel from a system memory.
4. The capacitive sensing device of claim 3, wherein the ACSS is further configured to transfer the sensor data through the DMA channel to the system memory after the first scan or the second scan of the frame for the processor to process the sensor data when the processor is interrupted.
5. The capacitive sensing device of claim 1, wherein the ACSS comprises a local memory configured, prior to the start frame event, by the processor to store sensor configuration for the plurality of scans of the frame, and wherein to load, without intervention by the processor, the first sensor configuration or the second sensor configuration, the ACSS is configured to load the first sensor configuration or the second sensor configuration from the local memory.
7. The capacitive sensing device of claim 6, wherein the processor is in a low power mode when the ACSS is configured to perform the first scan or the second scan of the frame, and wherein the processor is awakened from the low power mode when the processor is interrupted by the ACSS to process the sensor data.
8. The capacitive sensing device of claim 1, wherein the ACSS is one of a plurality of sensing subsystems configured to simultaneously scan the capacitive touch interface, and wherein the ACSS is further configured to perform the first scan or the second scan of the frame synchronously with the plurality of sensing subsystems.
12. The method of claim 11, wherein the first sensor configuration corresponds to a first scanning resolution and the second sensor configuration corresponds to a second scanning resolution.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
August 3, 2021
January 17, 2023
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